Zero Trust Network Security

Core principles of Zero Trust network security

Zero Trust is not a product but an architectural approach that defines how access decisions are made. In the traditional model, users inside the network are trusted; in Zero Trust network security, location is not a reason for trust. In practice, four principles stand out:

• Continuous verification: access is evaluated not only at sign-in but throughout the session, as user identity, device posture and context (location, time, risk signals) change.
• Least privilege: every user and service account can access only the application it needs, for only as long as it needs it; standing admin privileges are reduced.
• Micro-segmentation: the network is divided into small zones at the workload and application level, making it harder for a compromised device to spread to adjacent systems (lateral movement).
• Assume breach: all access is logged and monitored, and the design assumes that any account could be compromised.

These principles apply not only to employees but also to service accounts, API connections, vendors’ remote access and branch devices. In a Zero Trust design, human and machine identities are evaluated by the same policy engine; whether an access request is allowed is decided by weighing identity, device and context signals together.

ZTNA vs. traditional VPN

ZTNA (Zero Trust Network Access) is Zero Trust applied to remote access. The key differences from a traditional VPN:

ZTNA can be implemented with products from vendors such as Fortinet, Palo Alto Networks, Cisco and Microsoft; your existing firewall infrastructure is often the starting point for the transition.

A phased Zero Trust roadmap

1. Identity foundation: MFA for all users, a central identity provider and separation of privileged accounts.
2. Device trust: a corporate device inventory, endpoint security and device compliance conditions.
3. Application access: application-based ZTNA access instead of VPN, starting with critical applications.
4. Segmentation: splitting server and workload traffic into micro-segments and shutting down unnecessary east-west traffic.
5. Monitoring and improvement: analyzing access logs with SIEM and log management and tightening policies based on usage data.

Each phase builds on the output of the previous one: you cannot write application access policies before device trust is defined, and you cannot set up segmentation rules correctly without an application inventory. Rather than affecting the whole company at once, the transition is first piloted in one department or on one critical application; the scope is expanded after observing the user experience and help desk tickets.

To measure success, a few indicators are set from the start: the share of users covered by MFA, the number of accounts with standing admin privileges, the number of applications accessed via ZTNA instead of VPN, and the number of allowed connection rules between segments. Tracking these indicators regularly keeps Zero Trust an ongoing security model rather than a one-off project.